The discipline of transfusion medicine has recently undergone significant change. New data have resulted in changes in the evidence base and accordingly in recommendations, yet clinical practice has lagged behind, resulting in substantial practice variation. However, improving the appropriate use of blood products remains a challenging endeavor because physicians have strongly held beliefs in this area. Another part of the challenge is bringing evidence-based guidelines into the busy practice of hospital medicine. In response to these needs, we have designed a study that will first evaluate the barriers to adopting and implementing newly developed evidence-based transfusion guidelines at an academic medical center. We will further examine whether real-time computerized decision support of these guidelines can improve adherence. This knowledge will then be used to refine the education and dissemination of the guideline and decision support tools. Finally, we will study the impact of an education program for these transfusion guidelines followed by a decision support program for ordering blood products. Computerized physician order entry provides a valuable opportunity for assisting the clinician in the transfusion decision-making process. We will examine whether a decision support tool incorporating both clinical and laboratory information will improve the appropriateness of transfusion decisions as well as the utilization of blood products while maintaining excellent outcomes. We will also examine whether improvements in appropriate transfusion ordering behavior among clinicians using decision support tools will be greater than improvements achieved by educational programs alone.